The day after Monica Ramirez's siblings discovered she'd been in a horrific car crash in west Houston, they said they'd found one bright spot: the birth of her baby before she died.

"She fought long enough for her baby to be here," said Briana Church, Ramirez's 21-year-old sister. "Ellie is our miracle."

Investigators are still piecing together all of the circumstances behind the deadly crash, which took place about 2 a.m. on New Year's Day and involved her boyfriend, with whom she had a tumultuous relationship, relatives said.

The 25-year-old woman was driving south on the West Sam Houston Parkway in a Dodge Ram pickup and somehow collided with the black Cadillac CTS-V her boyfriend was driving, forcing both to leave the roadway and slam into a building on the 1900 block of the parkway's feeder road.

Ramirez was ejected from the truck. Medical personnel took both drivers to Memorial Hermann Hospital, where Ramirez, who was about six months pregnant, had emergency surgery to deliver her baby. The newborn remains in the hospital's neonatal intensive care unit.

Anton Aleksandrov, 24, the other driver involved in the crash, has since been released from the hospital, Ramirez's siblings said.

No charges have been filed against Aleksandrov, police said, who added that the crash is still under investigation.

Police told reporters Thursday the couple may have argued before the crash.

"This is a loss I've never felt before," the woman's brother, Joe Ramirez, wrote hours after her death.

His younger sister had been a loving mother, devoted to her 6-year-old son, Tyler.

"She was supportive of making sure he did well in school," the 26-year-old brother said.

For the family, the survival of Ramirez's premature baby was the one balm to ease the sting of her death.

"It's the one positive thing we can get out of this, that her baby is doing well," the brother said.

Joe Ramirez said he believes his mother will take custody of the little girl after she is strong enough to leave the NICU.

In the meantime, family are still sorting out funeral arrangements.

The father of the 6-year-old, Woodrow "Lex" Nellis, said he was told about Ramirez's death shortly after picking up their son.

"The first thing I thought, I'm going to have to tell my son his mother isn't coming home," said Nellis, a professional dog trainer.

He said he met Ramirez in 2007 in a park in Westbranch, in northwest Houston. He was taken by her beauty, he said.

"She came over and asked for a cigarette ... after that, we didn't spend a day apart for months," he said. He was 19. She was a year younger.

They married soon after they met, but later separated. They filed for divorce, but it was never finalized, he said.

Ramirez, a slim brunette with striking dark eyes and a penchant for posting glamour shots of herself on Facebook, had gone to school to be a hair stylist. She'd dreamed of a career modeling or in fashion design.

"She was searching for a path," Joe Ramirez said.

In 2013, his sister began dating Aleksandrov, a tall and lanky man from Yekaterinburg, Russia, according to his Facebook page.

Nellis said Ramirez stayed in touch with him, calling to talk about issues regarding their son. She also sometimes called him complaining of abuse. Just before Thanksgiving 2013, for example, she called him and asked him to take her to her mother's house after she fought with Aleksandrov, he said.

They had a tumultuous relationship, Nellis and Joe Ramirez said.

Reached by phone, Tatyana Aleksandrova, Aleksandrov's mother, said little. Her son had not been seriously injured, she said. Still, his life had been forever changed.

"How will he be OK?" she said.

Court records also show at least one serious incident of violence, in August, when Aleksandrov was arrested and charged with assaulting Ramirez. In the incident, he attacked her, dragging her on the ground, kicking her and stomping on her, according to court records.

After the incident, prosecutors sought an emergency protective order against him, forbidding him to go within 200 feet of Ramirez.

Joe Ramirez said investigators had not given him all of the details about the fatal crash.

Grieving for his sister, Ramirez said he thought her death would weigh heavily on Aleksandrov.

"I'm sure he cared about my sister," the brother said. "I'm sure knowing he had a part to do with (her death) will always be there. It will never go away. He has to live with that."

St. John Barned-Smith joined the Houston Chronicle in 2014 and covers public safety and major disasters, including floods, bombings and mass shootings. Barned-Smith came to the Chronicle after a stint in the Peace Corps and after reporting in Philadelphia and suburban Maryland. Follow him on Twitter or email tips to st.john.smith@chron.com.